Cold beer lovers should thank hybrid yeast from Patagonia that hitchhiked to Bavaria

Considering that beer is the most widely consumed alcoholic beverages, it may come as a surprise that scientists are still uncovering new information about the origins of popular drink.

Researchers from the University of Wisconsin-Madison (UW-Madison) have found new information about the mysterious cold-adapted yeast used to make lager. Among all the types of beer currently available, lager is the most popular. This type of beer is made using fermentation and brewing process that works at low temperatures.

In a previous study conducted in 2011, scientists have identified a type of South American yeast that is said to be one of the ancestors of the cold-adapted yeast used to make lager. This special yeast seems to have made its way from Patagonia to Bavaria, where it was combined with the typical domesticated yeast used to make beer. The combination of the two types of yeast led to the development of a hybrid, cold-adapted yeast used in the process of making lager.

The new study by UW-Madison researchers, has confirmed the claims made in the previous 2011 study. The new findings indicate that Saccharomyces eubayanus, a native Patagonian yeast, was one of the ancestors of the hybrid yeast used in lager production. The team published its findings in the journal Molecular Ecology.

"This yeast really is native to Patagonia," said Chris Hittinger, a professor of genetics from the UW-Madison. "We found two major populations that seem to be distinct. The trees they're associated with seem to provide everything they need. They're happy there." Hittinger was the lead researcher of the team that conducted the new study. He was also part of the original team that conducted the 2011 study on the Patagonian yeast.

Over the past 500 years, both scientists and brewers have been wondering about the origins of the hybrid yeast used to make lager. Despite massive advances in fermentation technology, scientists are still trying to develop more useful strains of yeast and other microbes that can be used in the fermentation of a wide variety of products. Modern fermentation is used to create industrial chemicals and compounds such as biofuel as well as food and beverages such as wine, beer and even soy sauce.

"Yeasts are important for fermenting processes and biotechnology," said David Peris, a UW-Madison genetics postdoctoral research associate. "The value of studying diversity is that you can pull out genes or strains that can be used for a particular industrial process." Peris is one of the co-authors of the study.

While Saccharomyces eubayanus is abundant in Patagonia, scientists say that the yeast has already reached North America. In fact, the yeast has also been found in Wisconsin at a location in Indian Mound Park. The find is said to be the first time that the yeast has been found in the wild in the US. The researchers say that the most likely scenario explaining the yeast's appearance in Wisconsin involves some type of accidental introduction.

"If I had to bet, I'd lay money on ski bums or migrating birds (as the agents responsible for transporting the microbe to Wisconsin)," said Hittinger. "What we think is happening is that well-established, genetically diverse populations are sending migrants around the world. Generally, they're not successful, but occasionally they are."